I know many people on this forum tend to rack from the bucket into a carboy with a bung and airlock fairly early in the process - when the wine in the bucket has dropped to just below 1.030 but one problem you can have when you do that is that much of the yeast may be living towards the bottom of the wine and if you rack off the lees you may be leaving behind a large percentage of the active yeast culture to together with a lot of the nutrients the yeast uses to repair their cells. I would go with Turock's advice and rack from the bucket into your carboy when the wine is closer to 1.000 rather than when there is still as much sugar in there to give you a gravity reading of 1.030. If you rack too early I think that is one reason why fermentations sometimes stall.
However, if you rack at 1.000, you risk the wine becoming oxidized because there isn't much CO2 being produced at those levels. I think 1.020 to 1.010 is a much "safer" racking point, and I also make sure to get a good slug of sediment when I rack, just leave behind that which will not go through the racking cane.
Now, on later rackings, keep the sediment out of the racking cane.